The present invention relates to a coupling device for coupling the various pipes forming a fluid circuit in a motor vehicle to one another or to other elements (filters, pumps, tanks).
The fuel circuit of a motor vehicle is an element to which motor manufacturers devote a large amount of attention in terms of safety. In the event of an accident, a rupture in this circuit considerably increases the risk of the vehicle catching fire. It is therefore appropriate to provide circuits that can withstand the accident-simulating impacts to which these circuits are subjected during testing. This requirement also applies to other vehicle fluids such as brake-fluid or power-steering circuits.
So far as couplings are concerned, it appears that metal devices behave in satisfactory manner.
However, for reasons of expense, it is out of the question to make such couplings by machining. It is therefore necessary to envisage fabricating them out of sheet metal, using fabrication methods of the stamping, hydroforming type associated with methods of cutting, folding, and bending.
Sheet-metal work involves intrinsic limits, e.g. concerning the geometrical shapes that can be obtained, the minimum dimensions that can be achieved, the resulting surface qualities, compliance with close tolerances. In addition, it is not possible to achieve sharp angles, such that connections by means of a spigot with sharp-edge peripheral portions in relief can be replaced only by a spigot with beads or bands in relief that require an external clamping collar.
It follows that a metal coupling produced using fabrication methods that are compatible with the market, i.e. by sheet metal working, present drawbacks compared with a coupling made of a plastic material, in particular in terms of overall size.